One of my goals as an instructor and as a textbook author is to help students understand how natural selection works. It’s such an elegant concept that it should be simple to teach and apply. But students come in with deep-seated misconceptions that are extremely difficult to dislodge. For example, if asked to explain why cheetahs run so fast, many will respond that cheetahs got faster and faster because they had to outrun their prey in order to survive.
I think most people’s exposure to this kind of evolutionary “magical thinking” probably comes from the mass media. A case in point is the recent finding that coating insecticides with glucose selects for cockroaches that avoid sweet-tasting substances. Here is the BBC account of the story. Scientifically, it’s a fascinating story because the phenomenon — sugar avoidance — is traced all the way down to a change in the taste receptors.
The issue is not the story itself but the way it is being reported and promoted. One problem is language that implies that cockroaches are evolving with the explicit goal of evading our poisons. The BBC’s headline in the story linked above is “Cockroaches lose their ‘sweet tooth’ to evade traps.” The New York Times article on the same subject is headlined Wily cockroaches find another survival trick: Laying off the sweets. The Christian Science Monitor’s story was entitled How cockroaches are evolving to avoid sweets. The Denver Post: Cockroaches quickly lose sweet tooth to survive.
These headlines all reinforce the common misconception that cockroaches evolved an aversion to sweets on purpose or that they had to evolve. The Denver Post is most blunt: the cockroaches have evolved to survive. If you understand natural selection, you know the insects are not doing this on purpose, and certainly not because they “had to.” You also know that the individuals aren’t changing just because insecticides are present. Instead, the poison simply kills the bugs that eat it; those that refuse the bait survive and reproduce, making more roaches with the same inherited aversion. The real explanation is beautifully simple, and no magical thinking is required.
The other problem is the implication that the cockroaches used intelligence to solve their poison problem. The New York Times headline refers to “wily” cockroaches. Other stories called the insects “clever,” and still others talked about the cockroaches “outsmarting” our traps. A reporter on a BBC radio program asked a scientist whether this finding indicates that roaches are more intelligent than previously thought. To his credit, the scientist explained that the phenomenon has nothing to do with intelligence. But the question itself reveals the misconception that evolution either requires, or is enhanced by, the ability to devise clever solutions to difficult problems.
Part of the blame also goes to sloppy language by biologists who should know better. For example, some introductory biology textbooks repeatedly describe evolutionary processes as a series of clever solutions to environmental challenges. While that approach to teaching evolution can be concise and appealing, it also leads students away from the truth about natural selection.
How can we help our students become “biologically correct” in thinking and writing about natural selection? We can’t change the mass media, but we can change our own language. Let’s stamp out the following phrases in talking about evolution and natural selection:
- overcoming challenge X by devising solution Y
- evolving adaptation X “in order to survive”
- any reference to a characteristic existing because it “solves a problem”
- references to cleverness, trickery, or devious thinking
- any reference to individuals “finding a way” to get out of a challenging situation
I am sure there are more examples; what would you add to this hall of shame?
P.S. Someone needs to invent a biological “auto-correct” app for Word. If it put a squiggly red line underneath the phrases listed above, it would be a great training tool for students as they learn the proper way to think about natural selection. Teachers could use it to track student progress and to pinpoint evolution misconceptions that are common in the class. Some academic authors would probably benefit from it too. Come on, you tech-savvy blog readers! Let’s see what you can do!